It allows you to :
Choose whatever your pdf is.
Assign a title and a descriptive image to your pdf.
Add bookmarks to pages in your pdf.
You can add an audio with your pdf to listen while you're reading.
You can add document (doc , docx) to your pdf to view while reading.
Also enforced with TTS (Text to speech) to listen to your doc file.
You can add custom notes to every page in your pdf.
Also , gives you statistics of how many hours have you read a certain PDF , when was the last time you opened it and when did you create the file.
No internet access needed , all stored locally.